"""



"""


class People:
    def run(self):
        print("人类在跑")

class Dog(People):
    def run(self):
        print("狗在跑")

class Cat(People):
    def run(self):
        print("猫在跑")


class Car:
    def run(self):
        print("车在跑")


mycat = Cat()
print(isinstance(mycat,Cat))
print(isinstance(mycat,People))

# 使用People里面的属性，无法做到类型限制，只能起提示作用
def who_can_run(obj:People):
    obj.run()
